We examined the effects of parent adherence on child outcomes in two treatment strategies for the Predominantly Inattentive Presentation of attention deficit/hyperactivity disorder (ADHD-I): behavioral parent training adapted for ADHD-I (Parent-Focused Therapy [PFT]) and a multicomponent intervention that combined PFT, a child life skills group, and a classroom intervention (Child Life and Attention Skills Program [CLAS]). In a 2-site randomized controlled trial, 199 children (7-11 years of age) were randomized to PFT (n = 74), CLAS (n = 74), or treatment as usual (n = 51). Parent adherence was rated separately by parents and clinicians. Child outcomes included ADHD-I symptoms and parent- and teacher- rated impairment social, organizational, and home impairment. Results from multiple regression analyses utilizing a composite of parent and clinician ratings showed that parent adherence predicted improvement in all 3 parent-rated child impairment outcomes and no teacher-rated outcomes in the PFT treatment group. Adherence ratings did not predict any parent- or teacher-rated outcomes in the CLAS treatment group and did not predict ADHD symptom change in either treatment condition. These findings suggest that when parents are solely responsible for teaching and reinforcing new child skills and behaviors (as in PFT), their adherence to the assigned intervention may be especially important for improvement at home. It may be less critical in multicomponent interventions, like CLAS, where the responsibility for teaching new child skills is shared among parents, teachers, and child group clinicians. Parent adherence does not appear to impact child improvement in the school setting.